As one who is fully committed to a career as an academic investigator, Dr. Isabel Lopez is an ideal candidate for a NHLBI Award for Minority Faculty K01. She is a solid scientist who is well trained in pharmacological and biochemical techniques, and has several high quality publications. K01 support for Isabel over the next several years in the laboratory of Dr. Lomasney will provide a transition from trainee to independent investigator. The training program for Isabel includes expanding her skills to include techniques of molecular biology and genetics. The strength of this training program we believe comes from the fact while there is continuity with Dr. Lopez's most recent work on phospholipases, she will be able to extend the work dramatically at Northwestern. Specifically Dr. Lopez will be able to dissect the functional domains of PLC using the techniques of molecular modeling and site directed mutagenesis, and at the opposite spectrum being to probe the physiological roles of various phospholipases by targeted mutagenesis in mice. It is hypothesized that the C2 domain of PLC delta1 is involved in membrane anchorage and processive catalysis by binding to phospholipids in a calcium dependent and perhaps regulated fashion. This hypothesis will be tested by site directed mutagenesis of residues implicated in phospholipid binding by molecular modeling. There is substancial evidence that PlC delta1 plays a role in mediating vascular smooth muscle tone, and that over stimulation of PLC signaling in the mypcardium leads to cardiac hypertrophy. We hypothesize that aberancies of PLC function will lead to hypertension and/or the development of cardiac hypertrophy in mice. Mutant PLC isoforms with enhanced and diminished function will be expressed in mice using both transgenic and targeted gene replacement strategies. The laboratory of the primary sponsor is set up to perform all the indicated studies. While there is great strength at NU in the area of signal transduction there is more limited expertise in mouse genetics. Therefore, applicant will spend time in the laboratories of Dr. Maeda and Smithies at UNC to perform the gene replacement studies.